Laser Raman spectra of biological membranes produce a signal very rich in detail and potentially very informative regarding membrane structure and function. However, the meaning of many parameters of this complex signal are still to be worked out. We approach this problem by several routes. This inculdes the stepwise removal, addition or alteration or proteins of the human erythrocyte membrane, as well as the systematic study of membrane vesicles, lipid components, model systems, and diseased membranes. We are developing model systems beginning with simple phospholipid vesicles and, by systematic addition of erythrocyte membrane proteins or parts thereof, are building simplified preparations. Monitoring the Raman spectra of these various stages is of aid in interpreting the more complex information that has been obtained from intact membrane preparations. A major problem has been the reproducibility of spectra from erythrocyte membranes. After considerable efforts highly reproducibility of spectra are now obtainable, which open up possibilities for study of more subtle variations and modifications of these membranes.